Cynics might say that Ken Livingstone's willingness to close the capital's busiest streets and turn them over to sports events and pop concerts is just a modern version of "panem et circenses" - simply a crowd-pleasing gesture by a weak emperor who fears the will of the people. And yesterday's announcement by the mayor of London, about the economic benefits that next year's staging of the Tour de France will bring, could be seen in that light.

Perhaps it's true because this particular pleb is easily bought. Being a card-carrying bike nut, I would vote for Ken just for bringing the Tour to London. But only because I also know that, under Livingstone, London has become a flagship for how a major metropolis should tackle the challenge of sustainable transport. Putting cycle sport centre stage and making cycling seem sexy, instead of merely worthy, has been an important plank in that larger policy aim.

In fact, the mayor's agency, Transport for London (TfL), has presided over a huge growth in spending on cycling in London's boroughs. This, combined with other measures such as more bus lanes and the congestion charge, has visibly boosted the number of cyclists on the city's streets.

And yet. We still lag far behind other European cities - the Berlins, Amsterdams and Copenhagens - in terms of cycle use. Here, we have only just begun to come up with the sort of stick-and-carrot solutions that will persuade people to stop driving everywhere and make that "modal shift", as the policy wonks put it.

Richmond's new parking permit scheme that penalises owners of cars with high carbon emissions is a useful stick, but where's the carrot? Ken will point to the record and say that TfL is spending £28m a year on cycling, but most people's experience is that cycle routes leave a lot to be desired. Bike lanes too often start and end arbitrarily. They are often best when you need them least - and as soon as you enter a busy road, they abandon you completely. There is nowhere near enough secure bike parking - too many people get their bikes nicked and give up then and there.

There are still too many roads where cars can speed with impunity, making adults unwilling to risk biking themselves, let alone encourage their kids to cycle. And that £28m, welcome though it is, is absolute peanuts in the grand scheme of public spending on roads. So, thanks for the circuses, Ken, but how about some of that bread?